At 2012-11-30 16:40 +0000, Costello, Roger L. wrote:
>Hello David,
>
> > The local part in that case is not referring to markup or an XML
> > vocabulary at all, it is just the identifier of an error, the identifier
> > is almost never used in XML markup.
>
>So,
>
> {http://www.w3.org/2005/xqt-errors} FOER0001
> {http://www.w3.org/2005/xqt-errors} FOER0002
> {http://www.w3.org/2005/xqt-errors} FOER0003
> ...
>
>is not an XML vocabulary but,
>
> {http://www.bookstore.org}BookStore
> {http://www.bookstore.org}Book
> {http://www.bookstore.org}Author
> ...
>
>is an XML vocabulary?
>
>Why?
Because an XML vocabulary is a set of elements and attributes whose
names can be qualified by namespace URI strings to distinguish them
from other elements and attributes. The error codes is a set of
values qualified by namespace URI strings to distinguish them from
other error codes created by the user.
>What distinguishes them that allows me to know this?
The context of how the URI strings are used, not anything in the URI itself.
The qualified name "{http://saxon.sf.net/}eval&quot; is used to identify
an extension function, not an element, nor an attribute, nor an error code.
>So the first set of xs:QNames is not an XML vocabulary but the
>second set of xs:QNames is an XML vocabulary?
No, any set of xs:QNames is a set of qualified names that, when used
properly, uniquely distinguish and may even identify what is being
named from other things that are also named.
>Why?
>
>I thought that -- by definition -- an XML vocabulary is a set of
>xs:QNames, where each local part has the same namespace URI part.
>
>No?
Not as I see it. An XML vocabulary is a set of element and attribute
names that may be qualified with namespace URI strings. In addition
the vocabulary may have one of many valid structures (one or more
document models (schemas/DTDs), perhaps many to cover the life cycle
of a document) and perhaps business rules that cannot be expressed as
schema constraints.
I understand the naissance of qualified names using namespace strings
was for elements and attributes. But as I said in an earlier post
because of their properties they have long been used for many things
such as XSLT extension function identifiers, which have nothing to do
with elements and attributes. The recent application of namespace
strings to identify error codes is just yet another application of
qualified names to take advantage of those properties. But that
doesn't make the error codes "an XML vocabulary".
It is just a naming convention with important properties of
distinction and possibly identification.
. . . . . . . Ken
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